Microsoft Threat Intelligence offers a comprehensive examination of threats targeting Microsoft Teams, outlining the strategies attackers use and providing practical mitigation steps to improve organizational security.

Mitigating Threats Targeting Microsoft Teams: Attack Chain and Defense Strategies

Author: Microsoft Threat Intelligence

Overview

Microsoft Teams is a prime target for both cybercriminals and state actors due to its widespread use and extensive collaboration features. This article details how attackers abuse Teams’ capabilities throughout the attack chain and outlines best practices and controls for defenders to proactively monitor, detect, and mitigate these threats.

Teams-Focused Attack Chain

Reconnaissance:

  • Exploiting Teams accounts managed by Microsoft Entra ID (formerly Azure AD).
  • Open-source tools (ROADtools, TeamFiltration, TeamsEnum, MSFT-Recon-RS) enumerate users, teams, groups, and tenant configurations.
  • Attackers leverage Team’s APIs and misconfigurations (e.g., anonymous and external access) for early reconnaissance.

Resource Development:

  • Adversaries may register or compromise legitimate tenants, spoof domains, and create convincing pretexts for social engineering by abusing Teams and Entra ID features.

Initial Access:

  • Social engineering (tech support scams, vishing, email bombing) facilitates the delivery of RMM tools, malware, and credential-stealers through Teams.
  • Attackers imitate internal personnel and deploy malware (e.g., DarkGate via TeamsPhisher) using fake Teams installers or malicious links.

Persistence, Lateral Movement, and Escalation:

  • Methods include using guest accounts, compromised tokens, admin abuse, and persistence mechanisms such as exploiting legitimate Teams admin tools.
  • Adversaries may leverage Graph API and tools like AADInternals for continued access to Teams and related resources.

Credential Access and Privilege Escalation:

  • Attackers collect and reuse valid refresh tokens, escalate permissions, and target MFA defenses through repeated prompts and social engineering.

Discovery, Collection, and Exfiltration:

  • Use of tools (GraphRunner, AzureHound) to access Teams conversations, enumerate configuration, and collect sensitive information for exfiltration.
  • Data is often exfiltrated via Teams chat, OneDrive, or SharePoint integrations.

Command and Control (C2):

  • Adversaries utilize Teams APIs and custom red-teaming tools (ConvoC2, Brute Ratel C4) to establish C2 channels via Teams communications.

Impact:

  • Includes extortion, financial theft, and direct communications designed to pressure incident response teams and extort ransom payments.

Mitigation and Protection Guidance

Identity Protection:

  • Enforce sign-in risk policies via Microsoft Entra ID Protection.
  • Require MFA and use Privileged Identity Management for just-in-time access.

Endpoint Security:

  • Use Microsoft Defender for Endpoint, Office 365, and relevant configuration analyzers.
  • Apply Conditional Access, attack surface reduction rules, and keep software up to date.

Teams Client & App Security:

  • Apply Secure Score recommendations.
  • Use Intune for endpoint protection, Safe Attachments/Links, and app-based Conditional Access.
  • Monitor external and guest access; manage Teams-specific security features (lobby, verification checks, app permissions, DLP).

Data Protection:

  • Enforce encryption, meeting sensitivity labels, and Microsoft Purview DLP policies.
  • Carefully manage SharePoint and OneDrive integration settings.

Awareness & Detection:

  • Conduct attack simulation training and developer education.
  • Leverage Defender XDR, Defender for Cloud Apps, Microsoft Sentinel, and Purview auditing for event correlation, advanced hunting, and incident response.

Recommended Hunting Queries:

  • Provided KQL queries for detecting data exfiltration, malicious content, phishing activity, external helpdesk impersonation, and Teams-related file access patterns.
  • Integration with Security Copilot for advanced analysis and hunting.

Microsoft Defender Detections (Examples)

  • Malicious sign-in attempts via risky IP or user agent
  • Teams chat containing malware, phishing links, or spam
  • Suspicious Teams access using Graph API
  • Compromised user accounts detected by password spray or MFA bypass attempts
  • Activity flagged by Defender for Endpoint, Office 365, or Cloud Apps

References

A comprehensive set of public resources and security research links from Microsoft and industry partners, covering techniques, detection tools, and incident analyses relevant to Teams threats.

Actionable Steps

  • Review Teams configurations and apply recommended hardening controls.
  • Monitor for indicators of compromise using the provided hunting queries and Defender alerts.
  • Educate users and administrators about common social engineering tactics targeting Teams.
  • Integrate Microsoft security platforms (Defender, Sentinel, Purview) for comprehensive detection and response.

For ongoing updates, consult the Microsoft Security Blog and follow the linked threat intelligence resources for the latest on emerging threats.

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